首先用实体框架代码映射同一类的子项 [英] Mapping child items of same class with Entity Framework Code First

问题描述

我试图使用EF Code First映射一个相当标准的类别模型

  public class Category 
 {
 public int ID {get;组; } 
 public int ParentID {get;组; } 
 
 public string Name {get;组; } 
 
 public Category ParentCategory {get;组; } 
 public List< Category> ChildCategories {get;组; 
} 
  

我有以下一些东西：

  modelBuilder.Entity< Category>（）
 .HasOptional（t => t.ParentCategory）
 .WithMany（） 
 .HasForeignKey（t => t.ParentCategoryID）
 .WillCascadeOnDelete（）; 
  

但这似乎没有照顾ChildCategories？

我是否缺少某些东西？

为了避免重复的问题参数，我遵循以下内容，但并没有完全回答我的具体查询： / p>

Code First Mapping for实体框架层次结构

实体框架CTP5 Code-First Mapping - 同一表中的外键

解决方案

将您的实体更改为

  public class Category 
 {
 public int ID {get;组; } 
 public int？ ParentID {get;组; } 
 
 public string Name {get;组; } 
 
 public virtual Category ParentCategory {get;组; } 
 public virtual IList< Category> ChildCategories {get;组; } 
} 
  

Make ParentID 可空，并允许 ChildCategories 加载，使其虚拟。

I'm trying to map a fairly "standard" category model using EF Code First

public class Category
{
    public int ID { get; set; }
    public int ParentID { get; set; }

    public string Name { get; set; }

    public Category ParentCategory { get; set; }
    public List<Category> ChildCategories { get; set; }
}

I've got something along the lines of:

modelBuilder.Entity<Category>()
    .HasOptional(t => t.ParentCategory)
    .WithMany()
    .HasForeignKey(t => t.ParentCategoryID)
    .WillCascadeOnDelete();

But this doesn't seem to take care of ChildCategories??

Am I missing something?

To avoid the duplicate question argument, I followed the following, however didn't quite answer my specific query:

Code First Mapping for Entity Framework Hierarchy

Entity Framework CTP5 Code-First Mapping - Foreign Key in same table

解决方案

Change your Entity to

public class Category
{
    public int ID { get; set; }
    public int? ParentID { get; set; }

    public string Name { get; set; }

    public virtual Category ParentCategory { get; set; }
    public virtual IList<Category> ChildCategories { get; set; }
}

Make ParentID nullable and to allow ChildCategories to be lazy loaded, make it virtual.

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